Quarato 2011 Biochim Biophys Acta
| Quarato G, Piccoli C, Scrima R, Capitanio N (2011) Variation of flux control coefficient of cytochrome c oxidase and of the other respiratory chain complexes at different values of protonmotive force occurs by a threshold mechanism. Biochim Biophys Acta 1807: 1114-1124. |
Quarato G, Piccoli C, Scrima R, Capitanio N (2011) Biochim Biophys Acta
Abstract: The metabolic control analysis was applied to digitonin-permeabilized HepG2 cell line to assess the flux control exerted by cytochrome c oxidase on the mitochondrial respiration. Experimental conditions eliciting different energy/respiratory states in mitochondria were settled. The results obtained show that the mitochondrial electrochemical potential accompanies a depressing effect on the control coefficient exhibited by the cytochrome c oxidase. Both the components of the protonmotive force, i.e. the voltage (ฮฮจ(m)) and the proton (ฮpH(m)) gradient, displayed a similar effect. Quantitative estimation of the ฮฮจ(m) unveiled that the voltage-dependent effect on the control coefficient of cytochrome c oxidase takes place sharply in a narrow range of membrane potential from 170-180 to 200-210 mV consistent with the physiologic transition from State 3 to State 4 of respiration. Extension of the metabolic flux control analysis to the NADH dehydrogenase and bc(1) complexes of the mitochondrial respiratory chain resulted in a similar effect. A mechanistic model is put forward whereby the respiratory chain complexes are proposed to exist in a voltage-mediated threshold-controlled dynamic equilibrium between supercomplexed and isolated states. โข Keywords: metabolic control analysis, oxidative phosphorylation, mitochondrial membrane potential, cytochrome c oxidase respiratory chain supercomplexes, HepG2
โข O2k-Network Lab: IT_Foggia_Capitanio N
Labels: MiParea: Respiration
Organism: Human, Mouse
Tissue;cell: Liver, Fibroblast
Preparation: Intact cells
Coupling state: LEAK, OXPHOS
Pathway: N, S
HRR: Oxygraph-2k
